GPP – General Purpose Permeation


VTI's GPP Accu-Flow™ model helium calibrated leak standard, which features a glass permeation-style leak element, is the most common leak for tuning and calibrating helium mass spectrometer leak detectors, leak testing systems, and vacuum systems. This particular model is part of a family of VTI calibrators that include the GPPT, GPC, and CLP calibrated leaks.  Together, these models cover leak-rates as small as E-12 and as large as E-3 atm-cc/sec, and larger. VTI's experts are always eager to help you select the best model for your application.

GPP Accu-Flow™ calibrated leaks are based on the principle that helium flows through certain materials at a measurable rate depending on the material thickness, driving pressure and temperature. Depending on the leak rate required in the GPP Leaks, the permeation material is either Pyrex or Quartz. For reliability, this leak features an all-welded stainless steel construction.

Most leaks require a shut-off “isolation” valve to zero the leak signal during tuning and calibration. VTI offers the GPP Leaks both with and without a Teflon®-packed stainless steel shut-off valve. The inlet port of the brand of leak detector or vacuum system determines the termination of the leak. The most common termination of the GPP Leaks is a 1-1/8” diameter tube which mates directly to many Varian, Veeco and VIC leak detectors.

All leaks are available with QF (NW, KF) and many other types of fittings. All GPP Leaks are provided with certifications of the NIST-traceable calibrations performed in our A2LA-accredited Calibration Laboratory.


  • Never clogs: permeation leak element eliminates the threat of clogging
  • Versatile: available leak-rates range from E-5 to E-9
  • Stable: low temperature coefficient of 4.0% per degree Celsius
  • Meets ISO requirements: NIST-traceable, A2LA-accredited Calibration Certification

Do you have any questions?